Control means for the nozzle outlet area of jet engines



Jan. 1, 1952 M. H. 1.. SEDILLE 2,580,962

CONTROL MEANS FOR THE. NOZZLE OUTLET AREA OF JET ENGINES Filed May 9, 1946 2 SHEETS-SHEET l Jan. 1, 1952 Filed May 9, 1946 M. H. L. SEDILLE 2,580,962 CONTROL MEANS FOR THE NOZZLE OUTLET AREA OF JET ENGINES 2 smms-sxmm 2 FUEL 8 INYENTOR MARCEL H. SEDILLE -BYI ATTORNEYS Patented Jan. 1, 1952 UNITED STATES AREA OF JET ENGINES Marcel Henri Louis- Sdiile; Paris, France,- as signer to Societe Rateau S'ociete vAnonyme), Paris, France, a company of France, and Ren AnxionnamParis, France I Application May 9, 194e,,seija1-No.-scs-,5s

In France June 13; 1945 6 Claims. (Cl. 035.6)

High speed vehicles, and in particular aircraft, may be driven by a reaction jet propeller the air compressor of which may include a first compressor constituted by a centrifugal arrangement or preferably by an axial compressor. The compressor is driven bya thermic engine including a second centrifugalor axial compressor, one or more combusion chambers with burners and lastly an expansion turbine. The air compressed in the first compressor and the exhaust gases from the turbine are then admixed inside the chamber, with or without additional heat being supplied by one or more complementary burners. The driving gases then expand through a reaction jet nozzle in a direction opposed to the movement of the vehicle.

The rate of operation of the propelling means depends on the altitude of flight and on the-speed ofdisplacement of the, vehicle, on the amount of fuel admitted into the burners andlastly on the arrangement of the different membersof the propeller including more particularly the cross-sectionalarea allowed for the operating fluid.

My invention has for its object asystem for adjusting the outlet cross-sectional .area of the reaction jet nozzle with aview to producing at eachmoment the best conditions of operation for thev propelling means; .it consists chiefly in means for automatic adjustment or if required for a hand adjustment of the position of the closing member of the reaction jet nozzle as a function of suitable parametric values.

. The following description given with reference to accompanying. drawings shown by way of .example and not in a limitative sense, will allow the execution of the invention to be easily understood';. the features appearing both in the drawing and in the specification forming of course,. part of said invention. In said drawmgs:

. Fig. I is a cross-sectional view of .a reaction-jet turbine for the propulsionof anaircraft'advancing ,at high speed. 7 I v Fig. 2Ishowsan automaticdevicefor adjusting the outlet cross-sectional area of the reaction jet nozzle.

Fig. 3 shows an indicator for the dash-'board-allowing the pilot to execute a hand-operated adjustment.

Fig. 3a shows the same reaction jet turbine as in Fig. 1, but provided with two hand actuated levers for controlling :the injection of fuel into the combustion chambers-and the closingmeans for the. reaction nozzle. 1

con id rin r act Jet o ll smeans comprising a turbine, said means being of the above disclosed type. It has :been assumed by way of example that the operating air is taken into the front of the propelling means with a relative speed equal to the speed of the aircraft V The fairing a of the machine includes at its frontuenda chamber b the cross-section of which increases gradually and inside which the air is submitted 1302, first -.compression through a dampingof its speed.- The operating air is then submitted to a firstm'echanic'al compression insidethe compressor Cr andthena fraction of this air which takes part in the cycle of the thermic engine'including the gas turbine is submitted to a second mechanical compression inside the compressor C2; Atthe outlet-from C2, the air is submittedto heating inside the combustion chamber Ca fed with one or more burners di and ex pands' while producing driving energy inside the gas turbine 13;; which provides for the driving of the" compressors :01 andCzt A portion of the air output delivered by C1 forming diluting air-.ismixedwith the combustion gases from the exhaust ofthe turbine tg, the .mixture zbeing formed inside a chamber m provided required with one or more burners d2. The gaseousimixture expands, finally, inside? the reaction :nozzle- Sr out of which it escapes at the speed V21;

As a modification, the fiow of air at .lowpressure or dilutingair may be done away with, in which? case'the {propelling means are fed with-a single stream of air which passes in succession through the compressor, the combustion chambers, theqturbine andthe reaction nozzle.

The outlet cross-section of the reaction jet nozzle is defined in" either case by the position of closing means of any desired shape.

It is apparent that with such asystem it may be of value to be able to adjust the cross-section of the reaction nozzle. This is the case in particular when the auxiliary burners dz are used as it is then necessary for the outlet cross-section of the reaction nozzle tobe increased in order to take into account the increase in volume of the gases produced through this reheating, if it is not desired to modify the conditions of operanew or the engine; a gas 1 turbine" having a constant exhaust-at itsoutlet.

Ge'nerzill'y speaking, it maybe stated that for a'givericross se'ction of the reaction jet nozzle,

the" speed of the propelling means depends on a certain number of variables including in particular the amount of fuel injected into the burners 5 di and (12, the speed of the aircraft and the altitude of flight. The different rates may be ascertained either experimentally or through calculation.

For any other value of the cross-section of the reaction-jet nozzle, there is obtained another series of rates of operation of the engine and it is possible to ascertain the cross-section of the nozzle adapted to produce the most suitable rates of operation. It is possible for instance to adjust the conditions of operation of the compressor so that it may operate at optimum efliciency for each speed while avoiding the zone of pumping, or else a constant temperature of admission of the gases into the turbine may be sought for or again any other conditions considered as expedient such as that consisting in the obtention of the maximum efficiency of the whole at all rates of operation.

It is thus apparent that the cross-section of the reaction jet nozzle should be a function of the above-mentioned parameters i. e. altitude, speed of the aircraft and amount of injected fuel, the function being necessarily complex but yet capable of definition experimentally or through calculation.

However, and as, generally speaking, the opening of the jet reaction nozzle reacts on the operation of the propelling means only through the agency of the pressure produced at the exhaust of the gas turbine, it is suflicient to conform with a law binding said pressure to the operation parameters of the propelling means themselves for obtaining a proper operation of the latter without taking into account the other variables. These parameters are then the pressure and the temperature at the suction of the compressor and its speed of rotation. Instead of the latter, it is possible to use in an equivalent manner the pressure prevailing inside the combustion chambers.

It is possible moreover to show that if the pressure and temperature at the suction end of the compressor vary, there are obtained rates of operation of the propelling means which are aerodynamically similar, i. e. for said rates of running the efliciencies of the difierent members are retained and the temperatures at the different points of the circuit remain in the same ratio, if the ratio between the pressures remains unvarying.

It is therefore suflicient if Pe designates the pressure ahead of the reaction jet nozzle, Po the pressure at the suction end of the compressor and P: the pressure inside the combustion chambers to conform with a law of the type:

P. g; FT a.)

that is to say the ratio is a function of the ratio said ratio and said function and the function o and, in the opposite direction, of a second impulse proportional to the function (a) The angular displacements of the lever considered are then proportional to a f a and are used for controlling the position of the closing means.

The first impulse is provided as follows: A lever L1 is pivotally secured to the point 01.

A pressure responsive device a'i transmits to the.

lever Li a displacement proportional to Fe, but its point of application A1 moves with reference to the pivot of the lever L1 through the action of a second pressure responsive device a"1 producing a displacement proportional to P0. As shown in Fig. 2, the displacement of the pressure responsive device a'i under the action of the pressure responsive device a"1 is assured for instance through the agency of an auxiliary motor Sfmr comprising a distributor of fluid under pressure t1 and a motive piston n moving into cylinder 112. The linear displacement of the end B1 of the lever Li is then proportional to the ratio The linear displacement of the point B1 is transformed into a force proportional thereto through an auxiliary motor S"m1 similar to the The linear displacement of the point B2 is transformed into a force proportional thereto through the agency of an auxiliary motor S"mz. Said force is applied to the cam C which in turn transmits a force depending upon --the shapeof said main to roller- 01 mounted on a cranked lever 'C apivotally mounted at Ca. Finally-the force is transmitted through spring to lever L0.

The lever L0 is thus submitted to an effort proportional to ing to the law P, 1: I f

The lever Lo must be thus its neutral position. If this is not the case, spring is adjusted for placing lever L0 in its neutral position. The device is thus adjusted. Any shifting with reference-to the law to befollowed correspondsto an angular displacement of L0 acting then through an auxiliary motor of any suitable mechanical, hydraulic, pn umatic, electric or the like type on theposition of the shutter of the reaction nozzle. Shown on the drawing is anydrculic c l nder I, h p sto h ac p throttle member U. Lever h moves a distribu tor 3 which conduits 4 or 5 admits fluid under pr sure on, ne side or 1 the other i o Said piston.

a View to defining the rate of operation of the propelling means, there are provided hereinabove pressure elements forming the most easily measurable elements. It is possible to choose other variables and instead of for instance it is possible to use the following ra os wh depend uponv Ff NT) Pa V a Ta in which expressions N designates the speed of rota n o h omp e sor. To he absolute temncratur c he. r r n the. ompre or. T t e. a so u e e eratur b i lc h exp sion nozale and I thefweight of air flowing through the cross-section per unit of time.

Similarly, instead of making use of the, ratio P; it, is p sib tou e a part al; c mpr ssion rati of; the m r ssor desi nated or nstance by etc.

inder operating throttle member- U; in order that the pilot may be capable of controlling such operations, it is sufficient that he may be capable of checking on a suitable indicator the fact that the operating law l Pa e; Pro. I17 is'actual-lyverifled. 1 l a Fig. 3' shows by way of example and by no means in a limitative sense an indicator of the above type capable of being carried on the dash board of the aircraft. The apparatus includes two indicator hands A and B centrally carried by a common axis shown in perspective view and the tips of which move in front of two graduated sectors ai and b1. The pressure responsive device c submitted to the pressure Po and displaces; a set 121 the two arms of which e and f carry respectively a pressure responsive device g which gives the hand A a displacement proportional to Fe and a second pressure responsive device it giving the hand B a displacement proportional to Pg. The responsive devices 9,]; act oh. he, han i's'thr ugh the agen o slides 0 b tf c o nts f a p ca i n of h r ssure b ha d mo e n c o danc w the isplace'mentsof the leverage d. Under such con dition the hand A indicates on the corresponding dial on a value proportional to The e a ut cn oihe dia o sectors 31 and b .v ar nec ed: hro a em f corr sp ndn ines such as; i f r which the, equation Benji is satisfied. Therefore when the injection of fuel and the position of the throttling member U are in such "a relation that the said equation is satisfiechha'nds A and 33' come in front of the respectiveends of a same line i: when thepilot variestherate of operation of the plant, by acting on lever L'aor L4 (Fig. 3a)- or both, the equation is no more satisfied and this-isindicated by the fact that hands A and B do no more lie on a same line, i. The pilot must then act on lever L so as to restore the correspondencyof the hands on a same line i;

What I claim is:-

1. In a jet propulsion unit-:=an-aircompr'essor, at least one combustion chamber fed with air under pressure from said compressor, a gas turbine fed with hot gases from said combos tion chamber and adapted to drive the 00111121168 sor, a jet forming nozzle receiving exhaust gases from said turbine, throttling means associated with said nozzle for varying the cross-section area of said nozzle, detecting means. esponsive to the pressure B0 on the suction side of said compressor, detecting means responsive. to the pressure P: in said combustion chamber, detecting means responsive to the pressure PB before the intake of saijd nozzle, and mea-nsfor operatin g said throttling means in response to said de a csm ns i -'su.ch l manner hat he, ratio 7 is a determined function of the ratio V l P, V

wherein Pe is the pressure prevailin inthe unit before the intake of said nozzle and Po the pressure prevailing on the suction side of said compressor, means responsive to the pressure ratio remains a determined function of 3. In a jet propulsion unit: an air compressor, at least one combustion chamber fed with air under pressure from said compressor, a gas turbine fed with hot gases from said combustion chamber and adapted to drive the compressor, a jet forming nozzle receiving exhaust gases from said turbine, throttling means associated with said nozzle for varying the cross section area of said nozzle, detecting means responsive to the pressure Pe prevailing in the unit before the intake of said nozzle, detectin means responsive to the pressure Po on the suction side of said compressor, detecting means responsive to the pressure P: prevailing in said combustion cham-- ber, means operatively connected with the first and the second named detecting means and responsive to the pressure ratio means operatively connected with the second and the last named detecting means and responsive to the pressure ratio and means for operating said throttling means so that the ratio remains a determined function of 4. In a jet propulsion unit: an air compressor, at least one combustion chamber fed with air under pressure from said compressor, a gas turbine fed with hot gases from said combustion chamber and adapted to drive said compressor, a jet forming nozzle receiving exhaust gases from said gas turbine, throttlin means combined with said nozzle for varying the cross-sectional area thereof means responsive to the ratio means responsive to the ratio n V. V P,

P0 being the pressure on the suction side of the compressor, Pe the pressure prevailing in the unit before the intake of said nozzle and P: the pressure in the combustion chamber, means for transforming the ratio into a force proportional thereto, means for transforming the ratio I El P,

into a force which is predetermined function of said ratio 5 P a a pivoting lever operatlvely connected to said throttling means for controlling it and means for applying to said lever in opposition the first named and the second named forces respectively. 5. In a jet propulsion unit: an air compressor, at least one combustion chamber fed with air under pressure from said compressor, a gas turbine fed with hot gases from said chamber and adapted to drive the compressor, a jet forming nozzle receiving exhaust gases from said turbine, throttling means combined with said nozzle for adjusting the cross-sectional area thereof, means for transforming the pressure ratio &

into a movement proportional thereto, means for transforming the pressure ratio into a movement proportional thereto, each transforming arrangement including an elementary lever, a stationary pivot for said lever, a pressure sensitive device submitted to the action of Pe or P: according to the transforming arrangement considered and adapted to displace its point of application on the correspondin elementary lever through a distance proportional to said pressure, and a second pressure sensitive device submitted to the pressure Po and adapted to displace the point of application of the first pressure sensitive device through a distance proportional to P0, a pivoting lever operatively connected to said throttling means in order to control it, a cam operatively connectedrto a point of the elementary lever of the second transforming arrangement corresponding to in order give a movement equal to a determined function of and a pair of elastic means connected respectively to a point of the elementary lever of the first transforming arrangement corresponding to P. and to said cam, said elastic means being further connected in opposition to a point of said pivoting lever; Pe being the pressure of the gases ahead of the jet forming nozzle, Po the pressure at the suction end of the compressor and Pr the pressure inside the combustion chamber.

6. In a jet propulsion unit: an air compressor, at least one combustion chamber fed with air under pressure from said compressor, a gas turbine fed by the combustion gases and adapted to drive the compressor, a jet forming nozzle, throttling means combined with said nozzle for adjusting the cross-sectional area thereof, means for transforming the pressure ratio "F, into a movement proportional thereto, similar means for transforming the pressure ratio 10 forming the displacement of a predetermined point of the corresponding elementary lever into a force proportional to a a P, P, according to the arrangement considered, a pivoting lever operatively connected with said throttle means in order to control it and submitted to the action of the first arrangement corresponding to and a cam submitted to the action of the second arrangement corresponding to REFERENCES 0 m) The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,402,363 Bradbury June 18, 1946 2,408,099 Sherman Sept. 24, 1946 2,409,176 Allen Oct. 15, 1946 

